The air pollution problems inherent in the operation of gasoline fueled and diesel oil fueled internal combustion engines are well known. For this reason various emission control devices are presently in use, and indeed are required by federal regulations, to reduce the amount of pollutants discharged into the atmosphere by internal combustion engines. These emission control devices, however, only remove a portion of the pollutants and are subject to deterioration with the passage of time. Also, they often hinder engines from operating at peak efficiencies.
Natural gas has been proposed as a substitute fuel for gasoline and diesel oil. It has the capability of producing less combustion pollutants and for decreasing engine operating costs without complex emission control devices. Obviously, its use would also reduce the rate of world fossil fuel consumption.
As the transportation infrastructure of today does not include large numbers of widely disbursed retail suppliers of natural gas for vehicles, it is not practical to produce vehicles that are fueled solely by gaseous fuels like natural gas due to range limitations. To evolve towards such it is more practical to equip vehicles with a supply of both a liquid fuel such as gasoline or diesel fuel and an auxiliary supply of gaseous fuel such as natural gas. To do that efficiently it is essential that as little retrofitting be done as possible to existing fuel intake systems and configurations.
Various devices have been developed for mixing natural gas and air for introduction into an engine. For example, conversion kits have been designed for installation onto carburetors. These kits provide a dual fuel system that permits operation of the engine on liquid fuel alone, on gaseous fuel alone, and in some systems on combinations of the two.
One type of such a kit provides a gaseous dispensing device mounted within an intake conduit that funnels air to the engine air filter. Exemplary of this type is that shown in U.S. Pat. No 4,494,515. A problem associated with this type of kit is that original automobile parts must be substantially modified in order to accommodate it. Once these modifications are made the modified part must be replaced or repaired, should the device be removed. Another problem associated with it is that the proper air to gas mixture is achieved through limiting the flow of gaseous fuel passing through the device into the engine air stream. This limitation results in limiting gas consumption rate throughout the entire range of gas flow rate needs.
Another type of kit achieves a proper mixture of gas and air by limiting the amount of air entering the carburetor. The mixture is adjusted by increasing or decreasing air flow by typically providing a movable plate which limits the spacing through which air entering the engine may flow. This limitation however results in limiting the performance of the engine. Exemplary of these types of devices are those shown in U.S. Pat. Nos. 4,425,140, 4,425,898, and 4,387,689. Once again, these devices require substantial modifications to be made to conventional parts of the automobile engine.
It thus is seen that an apparatus for mixing gaseous fuel and air together for introduction into an internal combustion engine without complex and costly modifications to the engine, and which may be easily adjustable so that the apparatus may be mounted to engines of different sized displacements, has long remained an elusive goal. Accordingly, it is to the provision of such that the present invention is primarily directed.